Fertilizing with Biosolids

Transcription

1 PNW 508 June 1998 $2.00 Fertilizing with Biosolids D. Sullivn Biosolids re y-product of municipl wstewter tretment. They contin orgnic mtter nd nutrients tht re eneficil for soil, crop, nd livestock productivity. Rw sewge solids must e processed to meet U.S. Environmentl Protection Agency (USEPA) stndrds efore they cn e clled iosolids. This puliction focuses on how iosolids cn e used to supply nutrients to crops. Other spects of iosolids utiliztion lso re ddressed riefly, including: Biosolids qulity fctors (trce element concentrtions nd pthogen levels) Applicle regultions Questions out iosolids sfety nd ppliction prctices Biosolids s Nutrient Source Nutrient content Biosolids usully re pplied t rtes designed to supply crops with dequte nitrogen. They lso contin other nutrients tht reduce fertilizer requirements. Tle 1 shows the typicl mcronutrient content of iosolids produced y Pcific Northwest wstewter tretment fcilities. The totl nutrient content shown in Tle 1 includes rpidly nd slowly ville nutrient forms. Inorgnic nitrogen (mmonium) nd sulfur (sulfide) compounds in iosolids re rpidly ville. Nitrogen nd sulfur-contining orgnic compounds re slowly converted vi microil ctivity to plntville forms. Field reserch in the Northwest hs shown tht out 40 percent of the totl sulfur (S) supplied y neroiclly digested iosolids ecomes ville during the first yer of ppliction. See Biosolids Nitrogen for detils on nitrogen (N) vilility for iosolids. Approximtely hlf of the totl phosphorus in iosolids is in inorgnic forms tht re rpidly ville for plnt uptke. This inorgnic P is present s Al, C, nd Fe phosphtes nd s Fe, Al, nd Mn hydrous oxides. These forms of P re similr to those formed shortly fter fertilizer P (C phosphte) ppliction to soils. Clcium nd mgnesium concentrtions in iosolids vry widely, depending on the hrdness of the locl wter supply nd whether lkline mterils re used in processing (see Soil ph ). All iosolids re low in potssium, which is wtersolule nd is removed with tretment plnt effluent (reclimed wter). For crop production, the mount of K needed from other sources (e.g., fertilizer, mnure) is not ffected y iosolids ppliction. Biosolids lso provide essentil micronutrients including copper, oron, molydenum, zinc, nd iron. Tle 1. Biosolids orgnic mtter nd mcronutrients (dry wt. sis). Nutrient Usul rnge Low High % % Orgnic mtter c Nitrogen 3 8 Sulfur Phosphorus Clcium Mgnesium Potssium Nutrient concentrtions re expressed on totl elementl sis; not ll elementl content is in plnt-ville form. Concentrtions for orgnic mtter, nitrogen, phosphorus, nd potssium re sed on 1995 Oregon Assocition of Clen Wter Agencies survey. Sulfur, clcium, nd mgnesium concentrtions re sed on iosolids nlyses from seven Pcific Northwest wstewter tretment fcilities. The usul nutrient concentrtion rnge includes pproximtely 80 percent of the iosolids nlyses reported. Biosolids composts nd lkline-stilized iosolids were not included in the clcultion of the usul nutrient concentrtion rnge. c Orgnic mtter s determined y loss on ignition (voltile solids). Dn Sullivn, Extension soil scientist, Oregon Stte University. Finncil support for this puliction ws provided y Oregon Assocition of Clen Wter Agencies nd Northwest Biosolids Mngement Assocition.

2 Blnce etween iosolids nutrient inputs nd crop nutrient removl The nutrients supplied y iosolids re not present in the sme rtio s they re found in plnt tissue. Therefore, iosolids supplied t n gronomic rte for nitrogen supply n excess of some nutrients (e.g., phosphorus) nd not enough of other nutrients (e.g., potssium). Tle 2 gives generl exmple of the reltionship etween iosolids nutrient inputs nd crop removl of nutrients. The generl nutrient lnce illustrted in Tle 2 (positive or negtive for prticulr nutrient) is vlid for most crops. Nutrients ccumulte in the soil to greter extent if nutrients re recycled onsite vi crop residues (e.g., grss mnged for seed production) or if hrvest is y grzing. Tle 2. Exmple: Annul chnge in soil nutrient sttus with 4-dry-ton-per-cre iosolids ppliction. Tll fescue grown for grss hy or silge. Biosolids Grss Net nutrient Totl nutrient nutrient input nutrient input removl to soil c pplied l/cre l/cre l/cre Nitrogen Phosphorus Potssium Sulfur Zinc Copper Estimted totl nutrient input with ppliction of 4 dry tons iosolids per cre per yer. Loss of 50 l N/cre s mmoni is estimted t ppliction. Bsed on field reserch in western Oregon nd Wshington (tll fescue hrvested four to five times ech yer, yielding out 1 ton of dry forge per hrvest). c Clculted s totl nutrient inputs minus grss hrvest removl. Leching losses of ll nutrients re ssumed to e insignificnt. Fertilizer replcement vlue of iosolids The tle elow estimtes the fertilizer replcement vlue of iosolids nitrogen, phosphorus, potssium, nd sulfur for the first yer fter ppliction. This estimte is sed on typicl iosolids nlyses nd estimtes of nutrient vilility from university field trils. The first-yer nitrogen vlue of 4-dry-ton/cre iosolids ppliction supplying 120 l ville N is pproximtely $36 per cre. The fertilizer replcement vlue for nutrients esides N depends on existing soil test vlues nd the cropping system. Typiclly, iosolids ppliction to meet crop N requirements elimintes the need for nnul P nd S pplictions. Biosolids hve the gretest fertilizer replcement vlue when they re pplied to soils testing low in ville P. The fertilizer replcement vlue clculted elow does not include the potentil enefits to soil qulity from iosolids (Tle 9). Soil qulity enefits re difficult to express in simple economic terms. Fertilizer replcement vlue per dry ton of neroiclly digested iosolids. First yer fter ppliction. Totl Aville Nutrient ` Expressed nutrient nutrient cost c Vlue per Nutrient s % dry wt. % dry wt. $ per l dry ton Nitrogen N $9.00 Phosphorus P $11.00 Potssium K $2.10 Sulfur S $0.48 Totl $22.58 To convert P nd K to units used in fertilizer mrketing: multiply P y 2.29 to get P ; multiply K y 1.20 to get K 2 O. Estimted plnt-ville nutrient relesed in the first yer fter iosolids ppliction. c Approximte nutrient cost is sed on Willmette Vlley ulk fertilizer prices, Mrch The ctul cost of pound of fertilizer N, P, or K vries depending on nutrient form nd nlysis (e.g., costs differ for nhydrous mmoni nd clcium nitrte s source of N), trnsporttion nd ppliction chrges, mrket conditions, nd the quntity purchsed. 2

3 Soil testing t iosolids ppliction sites Soil testing cn e used to monitor the chnge in soil fertility resulting from iosolids ppliction. For elements such s P nd Zn tht re reltively immoile, tke soil smples to depth of 12 inches, since test interprettions usully re sed on this depth (e.g., Mrx et l., 1996). For moile nutrients such s N nd S, smpling depth greter thn 12 inches often is recommended. When iosolids re pplied to perennil grsses or other cropping systems without tillge, smller smpling increments ner the soil surfce (e.g., 0-3 inches nd 4-12 inches) give etter informtion on chnges in nutrient vilility, soil ph, nd slinity (conductivity). To get the est informtion from soil testing, we recommend tht growers work with qulified gronomist to develop smpling pln to fit their cropping system nd iosolids ppliction techniques. Tle 3 shows n exmple of how soil testing cn help growers relize the gretest enefit from iosolids ppliction. In the exmple, soil test phosphorus nd zinc incresed s the mount of iosolids pplied incresed. After 3-dry-ton ppliction, soil test P nd Zn were well ove the minimum soil test vlues needed for drylnd whet (10 mg/kg icronteextrctle P, nd 0.5 mg/kg DTPA-extrctle Zn). Insted of repet pplictions t the sme site, more enefit would e otined y correcting P nd Zn deficiencies t other sites with low soil test vlues. Tle 3. Exmple: iosolids effects on soil test phosphorus nd zinc (drylnd winter whet). Soil test Biosolids (0 12 inch) Soil test pplied P Zn interprettion c dry ton/cre mg/kg d mg/kg P Zn medium possile deficiency medium sufficient high sufficient high sufficient Adpted from: Sullivn et l., Exmple dt represent the verge of four loctions in centrl Wshington cropped to drylnd winter whet. Soil ws smpled pproximtely 18 months fter iosolids ppliction. Averge iosolids P concentrtion ws 2.65 percent, nd verge iosolids Zn concentrtion ws 870 mg/kg (dry weight sis). Soil test phosphorus vi icronte extrction, zinc vi DTPA extrction. Soil test P nd Zn re indexes of soil nutrient sttus; they cnnot e used to clculte l of ville nutrient per cre. c Soil test interprettion from OSU Extension puliction, EC 1478, Soil Test Interprettion Guide (Mrx et l., 1996). d The units mg/kg re equivlent to prts per million (ppm) on dry weight sis. Applying more P to soils tht lredy hve high soil test P vlues is potentil environmentl risk. Runoff nd eroded sediment cn move P to lkes or strems, where it cn reduce wter qulity. At repet ppliction sites with high potentil for offsite P movement, soil testing cn help prevent excessive ccumultions of P. Biosolids Nitrogen Nitrogen forms Wstewter tretment fcilities routinely monitor iosolids mmonium, nitrte, nd orgnic N concentrtions. The orgnic N concentrtion is determined y sutrcting the mount of mmonium-n from totl N (TKN) concentrtion. Nitrte-N is present t insignificnt concentrtions in most iosolids, so it is ignored in the reminder of this discussion. The proportions of mmonium nd orgnic N in iosolids vry with the stiliztion process (e.g., digestion, composting) used t the wstewter tretment fcility (Tle 4). Aneroiclly digested liquid iosolids often contin more mmonium thn orgnic N. Other iosolids contin most of the N in orgnic form. Ammonium-N is ville to plnts immeditely fter ppliction. Orgnic N provides slow-relese N for crops fter ppliction. Tle 4. Effect of iosolids processing on N forms in iosolids. Ammonium Orgnic N N Moisture Percent of Processing content totl N content Aneroic digestion liquid Aeroic digestion liquid Aeroic/neroic digestion nd storge in lgoon > 6 months liquid Aneroic digestion nd dewtering semi-solid Drying ed solid Het-drying solid Composting solid Sources: Oregon wstewter fcility dt compiled y Oregon DEQ, nd 1995 Oregon fcility dt compiled y the Oregon Assocition of Clen Wter Agencies. Exmple using tle dt: For iosolids contining 4 percent totl N (dry weight sis), neroiclly digested liquid iosolids would contin pproximtely 2.4 percent mmonium N nd 1.6 percent orgnic N, while drying ed iosolids would contin pproximtely 3 percent orgnic N nd 1 percent mmonium N. 3

4 Plnt-ville Nitrogen Two processes ffect the mount of plnt-ville N (PAN) provided y iosolids ppliction: mmonium-n retention nd orgnic N minerliztion. These processes re descried riefly elow. Ammonium N retined fter ppliction When iosolids re surfce pplied (not incorported into soil t ppliction), portion of the iosolids mmonium-n is lost s mmoni gs. Ammoni loss is very rpid during the first hours fter ppliction. Estimtes of mmonium retention fter surfce ppliction rnge from 0 to 70 percent of the mmonium-n pplied. An estimte of 50 percent mmonium-n retention commonly is used for plnning purposes. Immedite tillge fter iosolids ppliction increses mmonium retined, ut is not prcticl or desirle for mny cropping situtions. Orgnic N minerliztion Orgnic N in iosolids is converted to plnt-ville forms (mmonium nd nitrte) y soil microorgnisms fter field ppliction ( process known s minerliztion). The iosolids tretment process ffects the orgnic N minerliztion rte fter lnd ppliction (Tle 5). Freshly digested iosolids usully contin more minerlizle N thn do iosolids produced with more intensive stiliztion processes (composting, long-term lgoon storge). Tle 5. Effect of iosolids processing technologies on first-yer orgnic N minerliztion rte. Processing First-yer orgnic N minerliztion rte Aneroic digestion Aeroic digestion Aeroic/neroic digestion nd storge in lgoon > 6 months Aneroic digestion nd dewtering Drying ed Het-drying Composting 0 20 The orgnic N minerliztion rte lso is ffected y soil temperture nd moisture conditions. Minerliztion is most rpid in wrm, moist soils. Minerliztion proceeds most rpidly immeditely fter iosolids ppliction, provided soil temperture nd moisture re fvorle. Usully, more thn hlf of first-yer N minerliztion occurs within the first 3 to 6 weeks fter iosolids ppliction. The quntity estimted for the first yer (Tle 5) represents cumultive minerliztion in 2 to 5 months in spring, summer, or fll. In winter, when soil tempertures re less thn 40 F, minerliztion is very slow. Soil nd plnt tissue testing cn e used to determine ctul N vilility fter iosolids ppliction. Repeted Appliction to the Sme Site The orgnic N not minerlized during the first yer fter ppliction is minerlized slowly in succeeding yers. Thus, when iosolids re pplied repetedly to the sme site, the nnul ppliction rte needed to meet crop needs is reduced. University field reserch with perennil grsses demonstrtes this slow-relese N contriution of iosolids (Tle 6). To compre fertilizer N to iosolids totl N, we use the term reltive effectiveness. At 50 percent reltive effectiveness, n nnul ppliction of 2 l totl N s iosolids is equivlent to ppliction of 1 l of fertilizer N. In the first yer of ppliction, iosolids totl N ws percent s effective s fertilizer N. In the second nd third yers of continuous ppliction, iosolids totl N ws percent s effective s fertilizer N. Thus, for the tll fescue exmple (Tle 6), iosolids ppliction rtes needed to equl n nnul fertilizer N ppliction rte of 200 l N/cre were l iosolids totl N/cre in yer 1, nd l iosolids totl N/cre in yers 2 nd 3. Tle 6. Reltive effectiveness of iosolids totl N for tll fescue production compred to fertilizer N Yers of continuous iosolids ppliction Biosolids Reltive effectiveness, Type Loction percent of fertilizer N Dewtered Puyllup, WA Het-dried Puyllup, WA Liquid Auror, OR Averge Biosolids were pplied t the sme totl N ppliction rte in yers 1, 2, nd 3 of ech study. Dt sources: Puyllup, WA, (Cogger et l., unpulished dt); Auror, OR, (Kiemnec et l., 1987). Reltive effectiveness in incresing hrvested grss N uptke. Reltive effectiveness of 50 percent mens tht current-seson ppliction of 2 l iosolids totl N ws equivlent to 1 l fertilizer N (mmonium nitrte, ). 4

5 Converting nitrogen vilility estimtes to ppliction rtes The estimted plnt-ville N (PAN) provided y iosolids ppliction usully is reported on dry weight sis (e.g., 1.5 percent PAN or 30 l PAN per dry ton). For field ppliction, solids never re dry. Fctors tht cn e used to convert n estimte of iosolids PAN to field N ppliction rte re shown t the right. To use these conversion fctors, you must know the percent totl solids content of the iosolids. For exmple, iosolids contining 98 percent liquid contin 2 percent totl solids. Converting from dry weight PAN estimte to ppliction units. To convert from % PAN, Multiply % PAN, dry weight sis to: dry weight sis y: l PAN/1,000 gl percent totl solids x l PAN/cre-inch percent totl solids x l PAN/wet ton percent totl solids x 0.2 Note: This tle converts from iosolids PAN s percentge of dry weight. If, on the other hnd, the municiplity lists PAN in terms of l/dry ton, divide y 20 to get % PAN on dry weight sis. For exmple, iosolids with estimted PAN of 30 l N/dry ton contin 1.5 percent PAN on dry weight sis. Exmples: Conversion from %PAN, dry weight sis to ppliction rtes A city produces iosolids with n estimted PAN of 1.7 percent (dry weight sis). The iosolids re pplied s slurry contining 4 percent totl solids. You estimte tht 100 l PAN/cre should e pplied to meet the crop yield gol. You cn clculte the mount of liquid iosolids to pply s follows: Exmple A: Conversion to gllons per cre Step 1. Convert % PAN on dry weight sis to ppliction units using the tle ove: Biosolids PAN (l/1,000 gl) = % PAN, dry weight sis x % totl solids x = 1.7 x 4 x = 5.67 l PAN/1,000 gl Step 2. Clculte the iosolids ppliction rte: Biosolids ppliction rte (thousnd gl/) = l N/cre l PAN/1,000 gl = = 17.6 (17,600 gl/cre) Exmple B: Conversion to cre-inches Step 1. Convert % PAN on dry weight sis to ppliction units using the tle ove: Biosolids PAN (l/cre-inch) = % PAN, dry weight sis x $ totl solids x = 1.7 x 4 x = 154 l PAN/cre-inch Step 2. Clculte the iosolids ppliction rte: Biosolids ppliction rte (cre-inches) = l N/cre l PAN/cre-inch = = 0.65 cre-inches 5

6 Soil ph Mintining n pproprite soil ph is essentil in mintining the productivity of cropping systems. Biosolids ppliction cn increse or decrese soil ph (Tle 7), depending primrily on whether lkline mterils re used in iosolids processing. Tle 7. Biosolids effects on soil ph. Type of Biosolids Effect on iosolids input soil ph Soil process Alkline- C oxides nd increse Converts soil stilized hydroxides cidity to wter nd cron dioxide. All solule slts temporry Ctions displce decrese cidity from soil clys nd orgnic mtter, ringing it into soil solution. All orgnic N nd S decrese Oxidtion in soil to nitrte nd sulfte produces cidity. All exchngele increse Supplies non- C nd Mg cidifying ctions. Alkline-stilized iosolids Some iosolids re stilized with lkline mterils (clcium oxide or clcium hydroxide) to reduce odors nd meet USEPA pthogen reduction requirements. In typicl lkline stiliztion process, the iosolids/ lkline mteril mixture reches ph of 12 or greter for t lest 2 hours efore ppliction. At this high ph, mmoni loss is rpid. Ammoni loss produces cidity, which neutrlizes some of the lkline mteril efore ppliction. After ppliction, the residul lkline mteril rpidly neutrlizes soil cidity, therey incresing soil ph (first process in Tle 7). Thus, lkline-stilized iosolids ct s replcement for griculturl limestone. Post-ppliction increses in soil ph, exchngele soil clcium, nd soil SMP uffer ph cn e used to determine the liming vlue of iosolids/ lkline mterils ppliction. Biosolids stilized without lkline mterils When iosolids tht do not contin dded lkline mterils re pplied, the chnge in soil ph is the net result of the lst three fctors listed in Tle 7. Shortly fter ppliction, drop in soil ph (cidifiction) my e oserved, usully 0.2 to 0.5 ph units. Acidity is generted y the ddition of solule slts nd y the oxidtion of orgnic N nd S compounds. This ph drop usully is short lived nd is lnced y the clcium nd mgnesium dded y iosolids. Becuse severl fctors re involved, soil testing is recommended to monitor soil ph t iosolids ppliction sites. The effect of iosolids vs. fertilizer N ppliction on soil ph is shown in Tle 8 for one Willmette Vlley ppliction site. The soil ph vlues listed were mesured fter 7 yers of iosolids or fertilizer N (mmonium sulfte) ppliction. The liquid neroiclly digested iosolids pplied in the study did not contin dded lkline mterils. The soil ph fter 7 yers ws the sme for iosolids ppliction nd for n nnul ppliction of 100 l N per cre s mmonium sulfte. Tle 8. Surfce soil ph (0 12 in) fter 7 yers of iosolids or mmonium sulfte ppliction to Willmette Vlley silt lom soil. Totl N pplied N Source l/cre/yr Soil ph None Biosolids Ammonium sulfte Source: Kiemnec et l., Loction: Auror, OR. Soil ph (0 8 inches) t the strt of the study ws 5.7. The soil hd ction exchnge cpcity of 15 meq/ 100g soil. Averge for neroiclly digested liquid iosolids from three Oregon wstewter tretment fcilities: Portlnd, Slem, nd Rock Creek (Unified Sewerge Agency, Wshington County). All iosolids sources in the study performed similrly. 6

7 Soil Qulity Biosolids ppliction lso ffects soil chemicl, physicl, nd iologicl properties. Together, these properties determine soil qulity. Biosolids supply oth nutrients nd orgnic mtter for soil qulity improvement. The orgnic mtter provided y iosolids does not y itself increse soil orgnic mtter gret del. However, when comined with other soil mngement prctices tht fvor ccumultion of orgnic mtter (e.g., reduced tillge, use of cover crops), iosolids ppliction helps improve soil qulity. The chnges in soil qulity ccompnying iosolids ppliction generlly improve the cpcity of crops to utilize nutrients. Potentil enefits of iosolids ppliction on soil qulity re listed in Tle 9. Tle 9. Wys tht soil qulity cn improve with iosolids ppliction. Physicl Greter wter-holding cpcity Improved tilth Reduced soil erosion Chemicl nd iologicl Incresed ction exchnge cpcity Plnt-ville nitrogen nd sulfur slowly relesed from orgnic forms Micronutrient deficiencies corrected Incresed erthworm nd microil ctivity To utilize the slow-relese N provided y iosolids, cover crops my e needed to cpture the orgnic N minerlized from iosolids in lte summer nd erly fll. Otherwise, this slow-relese N is likely to e lost vi nitrte leching. Wht out hevy metls? Hevy metls were concern when lnd ppliction of iosolids egn 25 yers go. However, since then, source control ctivities hve een very effective in decresing metl inputs to wstewter tretment fcilities: Wstewter tretment fcilities now issue permits to mjor industril wstewter sources nd routinely monitor metl concentrtions in the industril wstewter. To comply with permit requirements, industries hve dopted mnufcturing processes tht keep metls out of the sewer system. Adjustment of city wter supplies to higher ph hs reduced pipe corrosion nd the concentrtions of zinc, copper, nd led in household wstewter. The use of PVC pipe insted of metl pipe lso hs reduced metl concentrtions. The tle elow shows the impct of source control ctivities on iosolids metl concentrtions. Metls in Portlnd iosolids hve een reduced y fctor of 2 to 10 times over the pst 15 yers. Tody, iosolids metl concentrtions re similr for cities with industril inputs (Portlnd iosolids concentrtions, elow) nd smller tretment fcilities with few industril inputs (Averge Oregon iosolids concentrtions, pge 9). Decrese in metl content of City of Portlnd iosolids etween 1981 nd City of Portlnd iosolids Metl mg/kg mg/kg Cdmium 40 5 Copper 1, Led Nickel Zinc 2,

8 Crop Yield nd Qulity Biosolids fertiliztion often increses crop yield potentil over tht ttinle with other nutrient sources tht do not supply orgnic mtter or micronutrients. The most drmtic improvements in site productivity re oserved when iosolids re pplied to severely eroded croplnd. As with ny nitrogen source, over-ppliction of iosolids cn reduce crop yield nd qulity. Reserch with drylnd whet grown in the 10- to 14-inch nnul precipittion zone (est of the Cscdes) hs demonstrted tht iosolids pplictions tht supply too much N cn reduce grin yield nd qulity. Supplying too much N is less of crop qulity prolem for psture nd grss forge production, ecuse the N is utilized for incresed protein content. Biosolids rtes for woody vines nd tree crops should e monitored crefully, s N supplied in excess lte in the growing seson cn result in incresed winter injury. Forge Qulity Mcronutrients When similr mounts of ville N re supplied with iosolids or fertilizer N, the iosolids-fertilized forge usully hs higher phosphorus nd sulfur content (Tle 10). Unlike most diry nd poultry mnures, iosolids re low in potssium nd do not increse forge potssium, except when the typicl forge is nitrogen-deficient. Tle 10. Tll fescue mcronutrient concentrtions fter 4 yers of iosolids or fertilizer N ppliction. Nutrient concentrtion Grss grown Grss grown with with iosolids fertilizer N Nutrient mg/kg mg/kg Clcium Mgnesium Potssium Nitrogen Phosphorus Sulfur Tll fescue grown for grss silge, Puyllup, WA on Puyllup sndy lom soil. Biosolids were pplied t pproximtely 500 l totl N/cre/yr; fertilizer N (34-0-0) ws pplied t 300 l N/cre/ yr. Site soil test dt (0 12 in): Soil ph: 5.5. Exchngele C: 4 meq/ 100g; Mg: 1 meq/100g; K: 0.25 meq/100g. Phosphorus (Bry P1): 200+ mg/kg. For grss grown with fertilizer N, pplictions of K, Mg, nd S fertilizers were pplied to prevent nutrient deficiencies. Micronutrients Biosolids provide plnt-ville copper, zinc, nd mngnese. Biosolids ppliction cn help correct deficiencies of these elements in niml diets. Reserch with forge grsses (Tle 11) hs shown tht typicl micronutrient concentrtions in iosolids-fertilized grsses re fr elow levels considered detrimentl to niml performnce. Tle 11. Tll fescue micronutrient concentrtions fter 4 yers of iosolids or fertilizer N ppliction. Recom- Grss Grss Required mended grown grown concentrtion mximum with with in totl concentrtion iosolids fertilizer N diet in totl diet Nutrient mg/kg mg/kg mg/kg mg/kg Copper Mngnese ,000 Zinc Tll fescue ws grown t the sme site nd with the sme mngement descried in Tle 10. Required concentrtion in totl diet nd recommended mximum concentrtion in totl diet for eef cttle, sheep, nd horses. Source: Cuhn, Site Approvls for Biosolids Appliction Is site pprovl needed? Whether you need permit or site pprovl for iosolids ppliction to croplnd depends on: Trce element concentrtions in the iosolids reltive to USEPA stndrds Whether the iosolids meet USEPA Clss A or Clss B pthogen reduction requirements Site pprovls lwys re required for Clss B iosolids ppliction. More informtion on trce element nd pthogen reduction requirements is given on pge 9, Biosolids Qulity. Who otins site pprovl? When needed, site pprovls for iosolids ppliction generlly re otined y wstewter tretment plnt representtives. Some privte compnies, working under contrct with the wstewter tretment fcility, lso my ssist in otining site pprovl. 8

9 Biosolids qulity Biosolids qulity is sed on: Trce element concentrtions in iosolids The completeness of the pthogen reduction process used y the wstewter tretment fcility These iosolids qulity fctors re descried riefly here. Additionl detils cn e found in USEPA, 1993, nd Sullivn et l., Together, these two qulity fctors determine whether site pprovls y regultory gency re required for iosolids ppliction. Trce elements Current trce element concentrtions usully re well elow concentrtion stndrds set y USEPA for iosolids (see tle t right). The current concentrtions of trce metls in iosolids llow most wstewter tretment fcilities to produce eneficil product suitle for lnd ppliction. The USEPA stndrds, dopted in 1993, re sed on more thn 20 yers of field reserch nd comprehensive risk ssessment. The lower concentrtion stndrd for trce elements (Exceptionl Qulity Limit in the tle) is for iosolids products distriuted to the pulic. The higher concentrtion stndrd (Ceiling Limit in the tle) pplies to ll lnd-pplied iosolids. If one element in the product exceeds the Ceiling Limit, then the product cnnot e clled iosolids nd cnnot e lnd pplied. Pthogen reduction Pthogens re orgnisms, such s cteri, tht cn cuse disese in humns. Before ppliction to croplnd, iosolids must e processed to meet either USEPA Clss A or Clss B pthogen reduction stndrds. Clss A iosolids re essentilly pthogen-free nd usully re sold or distriuted in urn res for lndscping or turf fertiliztion. Becuse of the greter flexiility in mngement fforded y Clss Trce elements in Oregon iosolids in comprison with USEPA concentrtion limits for lnd ppliction. Oregon USEPA USEPA iosolids Exceptionl Ceiling Trce verge Qulity limit Limit element mg/kg mg/kg mg/kg Arsenic Cdmium Copper 589 1,500 4,300 Led Mercury Molydenum 8 75 c 75 Nickel Selenium Zinc 852 2,800 7,500 Averge concentrtion for 37 Oregon iosolids products s reported y the Oregon Assocition of Clen Wter Agencies (1995 dt). Source: USEPA guidelines for pollutnt concentrtions in iosolids (40 CFR Prt 503). The Exceptionl Qulity Limit pplies to iosolids suitle for distriution without site pprovls; the Ceiling Limit is the mximum for lnd ppliction of iosolids. To e clled Exceptionl Qulity Biosolids y USEPA, iosolids lso must e Clss A for pthogen reduction. c The USEPA Exceptionl Qulity Limit for molydenum currently is under review. A tretment, more fcilities re moving towrd Clss A iosolids production. Clss B iosolids hve een processed to significntly reduce, ut not eliminte, pthogens. Biosolids of Clss B qulity usully re delivered to frmers for lnd ppliction. The most common processing methods for Clss B iosolids re eroic or neroic digestion. Some tretment fcilities dd lkline mterils such s clcium hydroxide to kill pthogens nd meet Clss B stndrds. After lnd ppliction, pthogens in Clss B iosolids re killed y exposure to sunlight, drying conditions, unfvorle ph, nd other environmentl fctors. Site mngement prctices required t Clss B iosolids ppliction sites protect pulic helth. 9

10 Wht gency is responsile for site pprovls? Oregon: Deprtment of Environmentl Qulity Wshington: County helth deprtments nd Wshington Stte Deprtment of Ecology Idho: USEPA Site mngement prctices Tle 12 shows the site mngement prctices required for iosolids meeting USEPA s Clss A or Clss B pthogen reduction requirements. The dditionl site mngement prctices for Clss B iosolids ppliction sites protect pulic helth. Clss A nd B refer only to the completeness of pthogen reduction processes. Biosolids lso must meet stndrds for trce element concentrtion (see Biosolids Qulity, pge 9). For most crops, the witing period is 30 dys fter Clss B iosolids ppliction efore grzing or crop hrvest. For crops whose edile portion my directly contct the iosolids (e.g., root crops such s pottoes or crrots, nd low-growing vegetle nd fruit crops such s lettuce nd strwerries), the witing period etween iosolids ppliction nd hrvest is 14 to 38 months. Thus, Clss B iosolids ppliction is imprcticl for these crops. Tle 12. Site mngement requirements for Clss A nd B iosolids. Witing period efore Regultory Limit grzing gency Buffer Biosolids pulic or crop uthoriztion res clss ccess? hrvest? required? required? A no no no no B 365 dys 30 dys yes yes This tle gives generl explntory informtion on site mngement required y USEPA. For Clss B iosolids, the required site mngement prctices re included in site pprovls issued y the regultory gency. Privtely owned frmlnd meets the USEPA s definition of limited pulic ccess. 10

11 Questions out iosolids Wht limits the rte of iosolids tht cn e pplied? Appliction rtes re sed on supplying N for the crop, without excessive nitrte leching. Is there limit to the mount of iosolids tht cn e pplied to site? If iosolids meet Exceptionl Qulity (EQ) limits (see pge 9), there is no limit to the cumultive mount of iosolids tht cn e pplied. (Annul ppliction rtes re sed on crop N needs.) If one element exceeds the Exceptionl Qulity Limit, ut is elow the Ceiling Limit, then site life is sed on the cumultive mount of tht trce element pplied to the site. For most iosolids tht don t meet EQ stndrds, the clculted site life is more thn 50 yers. The mximum cumultive mount of trce element tht cn e pplied during site s life includes lrge mrgin of sfety. After the cumultive limit is reched, the site still will e productive for growing crops. Are permitted levels for hevy metls nd other trce elements likely to chnge in the future? The federl iosolids rule dopted y USEPA in 1993 ws sed on more thn 20 yers of university reserch. This reserch included numerous worst-cse studies, where sewge sludges contining high trce element concentrtions (2 to 20 times greter thn current concentrtions) were pplied t very high rtes (10 to 50 times the gronomic rte). The current iosolids regultions re sed on this extensive reserch se, nd re unlikely to chnge in the ner future. The Ntionl Acdemy of Sciences reviewed USEPA s trce element stndrds in 1995 nd pulished n extensive report concluding: While no disposl or reuse option cn gurntee complete sfety, the use of these mterils (iosolids) in the production of crops for humn consumption, when prcticed in ccordnce with existing federl guidelines nd regultions, presents negligile risk to the consumer, to crop production, nd to the environment. How ig of prolem re odors generted y iosolids ppliction? Odors produced y iosolids ppliction generlly re less thn for niml y-products such s diry or chicken mnure. The sme processes tht kill pthogens in iosolids (e.g., digestion) lso reduce odor fter ppliction. Tillge fter iosolids ppliction reduces odor. Wht concerns might my neighors hve out iosolids ppliction? Neighors my oject to potentil nuisnces ssocited with iosolids ppliction such s truck trffic, dust, nd odor. They lso hve concerns out protection of locl wter resources such s wells, strems, nd lkes. They lso my hve helth concerns. Biosolids trnsporttion nd ppliction prctices cn e modified to ddress neighor concerns. Ask the gency tht will provide the iosolids to visit with neighors efore the iosolids ppliction. How much time is required for iosolids ppliction reltive to conventionl inorgnic fertilizer ppliction? Biosolids ppliction is much slower thn conventionl fertilizer ppliction, ecuse of the lrge quntities of mteril involved. Severl weeks my e required to complete ppliction to lrge fields. Becuse of the slower pce of iosolids ppliction, perennil grss pstures re the most common ppliction sites. Annul crops cn e fertilized with iosolids, ut creful scheduling is required. If iosolids re vlule resource, why re they provided t no chrge to the lndowner? Not ll iosolids re free. Some municiplities chrge trnsporttion fee, n ppliction fee, or fee equl to the nitrogen vlue of the iosolids. In other cses, iosolids ppliction is free, which compenstes for lndowners time nd effort. Often, field opertions must e scheduled to ccommodte iosolids ppliction, nd mngement prctices specified y the regultory gency (see Tle 12) must e followed fter ppliction. 11

12 For More Informtion OSU Extension pulictions Huddleston, J.H. nd M.P. Ronyne. Revised Guide to soil suitility nd site selection for eneficil use of domestic wstewter iosolids, Mnul 8 (Oregon Stte University, Corvllis, OR). $3.25 Mrx, E.S., J. Hrt nd R.G. Stevens. 1996, reprinted Soil test interprettion guide, EC 1478 (Oregon Stte University, Corvllis, OR). $1.50 Sullivn, D.M Biosolids recycling in Oregon, EC 1471 (Oregon Stte University, Corvllis, OR). No chrge. To order copies of Oregon Stte University Extension Service pulictions, send the puliction s complete title nd series numer, long with check or money-order for the mount listed, to: Puliction Orders Extension & Sttion Communictions Oregon Stte University 422 Kerr Administrtion Corvllis, OR Fx: World Wide We: eesc.orst.edu You my order up to six no-chrge pulictions without chrge. If you request seven or more no-chrge pulictions, include 25 cents for ech puliction eyond six. Discounts re ville on orders of 100 or more copies of single title. Plese cll for price quotes. WSU Coopertive Extension puliction Cogger, C.G. nd D.M. Sullivn Worksheet for clculting iosolids ppliction rtes in griculture (Wshington Stte University, Pullmn, WA, in review). To order copies of Wshington Stte University Coopertive Extension pulictions, send the puliction s complete title nd series numer, long with pyment, to: Coopertive Extension Pulictions Bulletins Office Wshington Stte University P.O. Box Pullmn, WA Phone: e-mil: ulletin@coopext.che.wsu.edu World Wide We: Oregon Stte University WSU ccepts Vis nd MsterCrd (minimum $5.00 order), purchse orders (minimum $10.00 order), nd check (mke checks pyle to Coopertive Extension Pulictions). Government pulictions Sullivn, D.M., D.M. Grntstein, C.G. Cogger, C.L. Henry, nd K.P. Dorsey Biosolids mngement guidelines for Wshington Stte. Wshington Stte Deprtment of Ecology Puliction (Olympi, WA). USEPA Biosolids recycling: eneficil technology for etter environment, EPA Pul. 832-R (Office of Wter Resource Center, 401 M St SW (RC-4100), Wshington, DC 20460). USEPA A plin English guide to the EPA iosolids rule, EPA Pul. 832-R (Office of Wstewter Enforcement nd Complince). Reserch rticles ville from lirries Cogger, C.G., D.M. Sullivn, A.I. Bry, nd J.A. Kropf Mtching plnt-ville nitrogen from iosolids with drylnd whet needs. J. Prod. Ag. 11: Cuhn, T.J Slt nd trce minerls for livestock, poultry nd other nimls (Slt Institute, 206 N. Wshington St., Alexndri, VA 22314). Kiemnec, G.L., D.D. Hemphill, M. Hickey, T.L. Jckson, nd V.V. Volk Sweet corn yield nd tissue metl concentrtion fter seven yers of sewge sludge pplictions. J. Prod. Agric. 3: Kiemnec, G.L., T.L. Jckson, D.D. Hemphill, nd V.V. Volk Reltive effectiveness of sewge sludge s nitrogen fertilizer for tll fescue. J. Environ. Qul. 16: Ntionl Acdemy of Sciences Use of reclimed wter nd sludge in food crop production (Ntionl Acdemy Press, Wshington, DC). 178 pp. Sullivn, D.M., S.C. Frnsen, C.G. Cogger, nd A.I. Bry Biosolids nd diry mnure s nitrogen sources for pririegrss on poorly-drined soil. J. Prod. Ag. 10: Reserch rticle ville from Dn Sullivn Contct the Deprtment of Crop nd Soil Science, Oregon Stte University. Sullivn, D.M., A.I. Bry, J.A. Kropf, nd D.M. Grntstein Biosolids fertiliztion for drylnd Pcific Northwest whet production. p In: Proc. USEPA Biosolids Symposium, Effects of lnd ppliction of iosolids in rid nd semi-rid environments (Colordo Stte University, Fort Collins, CO, My 1995). Pulished nd distriuted in furthernce of the Acts of Congress of My 8 nd June 30, 1914, y the Oregon Stte University Extension Service, Wshington Stte University Coopertive Extension, the University of Idho Coopertive Extension System, nd the U.S. Deprtment of Agriculture cooperting. The three prticipting Extension Services offer eductionl progrms, ctivities, nd mterils without regrd to rce, color, religion, sex, sexul orienttion, ntionl origin, ge, mritl sttus, disility, nd disled vetern or Vietnm-er vetern sttus s required y Title VI of the Civil Rights Act of 1964, Title IX of the Eduction Amendments of 1972, nd Section 504 of the Rehilittion Act of The Oregon Stte University Extension Service, Wshington Stte University Coopertive Extension, nd the University of Idho Coopertive Extension System re Equl Opportunity Employers. $2.00 Pulished June 1998.